Inflation may be on its way down, but soaring prices over the past few years have put the budgets of households and community groups under pressure. Shopping around can reduce bills, but the really big savings can often only be achieved when commodities are ordered in large quantities – something that can be beyond the means of householders and small community groups. That's why some are joining up with other members of their community to reduce their bills by buying collectively.

Research by Co-operatives UK shows that almost 20% of people are buying co-operatively. This ranges from a few families clubbing together to buy organic food to vast heating-oil buying syndicates stretching across several counties.

There are many examples of thriving community buying groups around the UK. The high cost of heating oil has prompted the formation of individual buying groups and syndicates that buy on behalf of hundreds of communities.

In some rural areas, relatively few properties are on mains gas. This means that some households have to pay upwards of £300 in one go to purchase a minimum 500 litre delivery of kerosene. As a result of these prices, the incentive to club together has grown.

The Lower Swale Syndicate comprises eleven co-operatives serving villages clustered around Easingwold in North Yorkshire, with a combined membership of more than 800 households. In the past 12 months it has ordered more than 1.1 million litres of kerosene, achieving savings of around 3p per litre. By buying in bulk it allows customers to order smaller quantities than they would be able to buy alone and cuts pollution by reducing the number of tankers on the road.

Each co-operative is run by a volunteer co-ordinator, who collects orders from members and passes them on to the syndicate co-ordinator. The syndicate co-ordinator negotiates with suppliers and places orders on behalf of every member so that everyone benefits from the savings.

Chris Owens, a voluntary member of the syndicate says it can be difficult to wean some people in the community off the idea of loyalty to a supplier. "Sadly, they forfeit the chance to seek competitive quotations for a delivery, so the higher unit cost is compounded by uncompetitive pricing to a captive customer."

Another successfully operating heating oil syndicate is one organised through rural community councils (RCC) in England. Typically, people pay a £20 membership fee, which is waived if they volunteer as a local organiser. The funds from the membership fees go to their local RCC.

The network started as a buying group in the Oxfordshire village of Wootton and now has franchises in 28 English counties with Oxfordshire Rural Community Council providing the administration. It may also gain a partner network with the community action network Locality exploring how bulk buying will benefit its 700 members. Locality is currently in talks with the syndicate's buyer Community Buying Unlimited about ventures in Northern Ireland and rural areas.

While heating oil, LPG and other fuels have proved popular with community buying co-operatives, some groups are looking into greener products. The RCC syndicate plans to look at renewable energy once the uncertainty around feed-in tariffs is removed. In Greater Manchester, a group of residents are seeking to lower the cost of a move to low-carbon energy through bulk purchasing.

The Carbon Co-op wants to help neighbourhoods to come together to retrofit their houses through the purchase of low-carbon and energy-saving equipment. Any profits generated are reinvested in the co-operative. The more people join, the cheaper the products become.

The co-op is now bidding for up to £100,000 so that it can start putting co-operatively owned solar panels on roofs in the city. Project manager Jonathan Akinson says achieving savings to lower the cost of retrofitting is only one motivation. The other is encouraging community empowerment, he explains. "Our core is individual households but they work more efficiently through aggregating into groups, streets and neighbourhoods."

While community buying is often seen by its proponents as a way of opting out of conventional consumerism, some businesses are actually embracing it. One of these is the organic wholefoods supplier Suma, which works closely with co-operatives and buying groups.

Suma has sought to make its ordering process as simple as possible for buying groups by allowing different group members to put in orders. They have also invested in growing co-operatives by buying a stake in them and trying to provide advice to new groups whenever they can.

Rob Melling, a manager at Suma, says clients' enterprises often grow; yet very few buying groups become fully fledged co-operative stores. "We would like to see more people feeling confident enough to expand, partly because it is good for us. We would like to see more growth and more of a support network to allow growth. At the moment everyone is very isolated and people are continually reinventing the wheel."

Melling adds that co-operatives can fall apart when the workload is unevenly shared. One of Suma's clients, Bath's London Road Food Co-op, has been running for more than a decade. In recent years, its membership has dwindled after it lost some of the original members, but it remains an active supplier of organic and fresh food to residents of the city's north-east.

The Co-op opens every Wednesday in the Riverside Youth Centre, where orders are placed and food supplied. The group has its own cupboard and noticeboard in the centre, which allows it to store products and share information about organic food and lifestyles with co-operative members. Sometimes the event turns into a social occasion with tea and cake.

Cally Herbert, who collects members' orders, advises people interested in setting up a buying group to get as many people as they can involved and to delegate as much work as possible. "Because we are a co-op, we ask people to play a small part by volunteering. That seems to put some people off, but you need to create a bit of collective responsibility."

The community buying movement is still in its infancy but its biggest advocates believe it challenges the way commerce works. Chris Pomfret, who founded the heating oil buying group in Wootton, buys the fuel for the RCC heating oil syndicate. His local buying group started with heating oil but is now buying rock salt and compost.

"A community buying group can literally buy anything," he says. "The commercial world likes us isolated – they do not want us to come together. But two and a half years in, I do believe that I will never buy anything on my own again."